The invention relates to a method of identifying misuse of a seat belt in a vehicle as well as to a seat belt system of a vehicle.
In various countries it is obligatory to fasten seat belts in passenger cars during driving. In order to draw a passenger's attention to his/her failure of fastening the seat belt, sensors are known for detecting insertion of a plug-in tongue into the belt buckle or else webbing extension from the belt retractor. Unless either of said actions does happen, for example, a warning is output or even the use of the vehicle is inhibited (this is known as SBI or seat belt interlock).
Although the use of the seat belt definitely increases the traffic safety for the vehicle occupant, as is proven, there are repeatedly willful misuses of the seat belt system in which the seat belt is not fastened as intended. For example, the occupant may insert the plug-in tongue into the belt buckle and then sit on the seat belt. In order to bypass the belt buckle sensor, it may also happen that a separate plug-in tongue which is not connected to the webbing is inserted in the belt buckle. The use of such “cheating tongues” is intended to pretend fastening of the belt as intended. The sensor signals atone therefore provide no reliable information about whether or not misuse of the seat belt is given.